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2.1 Living organisms 2.1.1 Useful products Scientists are looking for new and improved products all the time. You need to be able to: identify useful products that can be made from living things. Foundation state that many useful materials are made from, or by using, living things: o from plants, we get cotton, pigments for dyes; chemicals to make drugs; o from animals, we get leather, silk, wool; o we use microorganisms to produce foods and medicines; state that fermentation is used in the brewing, baking and dairy industries; describe fermentation in yeast as a process that converts sugar and water into alcohol and carbon dioxide; know that fermentation is catalysed by enzymes found in yeast; describe an enzym Both Higher state the conditions needed for fermentation in yeast; describe how enzymes are involved in the brewing, baking and dairy industries, and in penicillin production; explain why fermentation works better under certain conditions; state the word equation for the fermentation of glucose: glucose → ethanol (alcohol) + carbon dioxide. state the balanced symbol equation for the fermentation of glucose. 2.1.2 Cells Cells are the building blocks of all almost all organisms. Plant and animal scientists study cells and the processes that go on in cells to learn more about life itself. Scientists called pathologists examine cells to look for harmful changes that can lead to diseases such as cancer. Other scientists culture cells that can be used for transplants and in techniques such as in-vitro fertilisation. Cutting edge, but controversial research on stem cells from human embryos may one day lead to the effective treatment of forms of diseases and injuries that are currently incurable. You need to be able to: describe living things as being made up of the same types of chemical compounds; state that the cell is a common feature of (almost) all living things. recall that all living things are made up from cells; identify the parts of cells and their functions: o nucleus . carries genetic information; o membrane . controls movement of substances in and out of cells; o cytoplasm . where many chemical processes happen; o chloroplasts . absorb light energy for photosynthesis; o cell wall . provides support; o vacuole . contains cell sap and helps provide support; state that chromosomes are held in the nucleus and that they carry information in the form of genes. explain that all living organisms are made up from chemical compounds and that the cell is the basic unit of life; describe the similarities and differences between plant and animal cells: o nucleus, membrane, cytoplasm in plant and animal cells; o chloroplasts, cell wall, large, permanent vacuole in plant cells only; recall that all living organisms are made up of carbohydrates, proteins, lipids and nucleic acid; explain why viruses to not conform to this model; state that chromosomes are strings of genes which instruct each cell and determines how the organism functions. state that genes are made of a chemical called DNA which carries the genetic code. 2.1.3 Dividing Cells Scientists study how cells divide. This is important when growing useful microorganisms such as yeast and when cloning important types of cells. You need to: understand that cells divide by mitosis during growth; understand that cells divide by meiosis when producing gametes or sex cells. explain that cell division is required for the growth of an organism; describe the nucleus of a cell contains long thread-like structures called chromosomes; o know that during the growth of an organism, or when a cell is cloned, cells divide by mitosis; o know that to produce gametes, cells divide by meiosis. explain that in multicellular organisms, growth is a combination of cell enlargement and cell division; when a cell divides by mitosis, two daughter cells are produced, each with a set of chromosomes identical to parent cell; explain the role of mitosis in cloning, and the scientific, moral, ethical issues of cloning human cells; understand why meiosis is required to produce gametes (which contain half the normal number of chromosomes. 2.1.4 Producing food from plants state that plants make glucose and starch by a process called photosynthesis; state that plants need carbon dioxide, water, light and chlorophyll to carry out photosynthesis; explain that glucose is converted and stored as starch; state that photosynthesis occurs mainly in the leaves; state that plants grow faster in the summer because of light and warmth; state the equation to describe photosynthesis: o carbon dioxide + water; o (+ light + chlorophyll); o → glucose + oxygen; explain that the glucose made by photosynthesis is transported as soluble sugars but is stored as insoluble starch; describe how photosynthesis can be increased by providing more CO2; more light; a higher temperature; state the balanced symbol equation for photosynthesis: o 6CO2 + 6H2O; o (+ light + chlorophyll); o → C6H12O6 + 6O2; explain the effects of limiting factors on the rate of photosynthesis (CO2, light, temperature) and how crop scientists use this understanding to increase plant yields; state that plants release energy by respiration: o starch is broken down; o oxygen is used from the air; o water and carbon dioxide are waste products; state that plants require nitrates (for proteins which are needed for cell growth); magnesium (for chlorophyll); potassium (for healthy growth and flowering); phosphates (for healthy growth, including root growth); explain and interpret data about plant growth in the presence or absence of these minerals; explain how competition between plants for light can reduce crop yields. using data, explain how high rates of respiration can reduce plant yields; state that plants also need minerals, which are found in the soil, for healthy growth; state that these minerals are absorbed in solution by the roots; recall the names of important minerals; nitrates, phosphates, potassium and magnesium; explain simple data about plant growth in the presence or absence of these minerals. state that minerals are taken up into roots by active transport; explain that active transport can move substances from low concentrations to high concentrations using energy from respiration; interpret data on research on factors affecting plant yields. 2.1.5 Farming methods Farmers who use intensive methods try to get maximum yields from their crops and farm animals. Organic farmers are concerned about the environmental impact of intensive methods. You need to be able to: describe how intensive farming increases crop yields and meat and milk production but makes an impact on the environment; describe the methods used in organic farming and their impact on the environment; identify the benefits, drawbacks and risks of farming methods. explain why intensive farmers can produce more food if they use: o artificial fertilisers; o herbicides; o pesticides; o fungicides; o meat produced in controlled environments; explain that these practices can cause harm to the environment and health. explain why intensive farming produces more food but: excessive use of artificial fertilisers can cause damage to the environment (eutrophication) and be hazardous to health (nitrates in drinking water); herbicides, pesticides and fungicides may enter and accumulate in the food chain; intensive farming of animals raises ethical dilemmas. explain how intensive food production improves energy transfer by reducing energy transfer: o to competing plants; o to pests; o as heat from farm animals by keeping them indoors; interpret data to explain why pesticides may accumulate in the food chain; explain how scientific thinking has changed/is changing, and some innovations in intensive farming have now been abandoned (the low toxicity of DDT to humans, but the discovery of its accumulation in food chains; the suggested link between high protein animal feed and BSE/CJD). recall that organic farming uses alternative methods: o natural fertilisers; o mechanical elimination of weeds; o controlling pests biologically by introduced predators; o keeping animals under more normal conditions. explain how organic farming uses alternative methods but that productivity may be lower: o natural fertilisers; o mechanical elimination of weeds; o controlling weeds and pests using natural chemicals; o controlling pests biologically by introduced predators; o keeping animals under more humane conditions. recall one advantage and one disadvantage of each type of farming. evaluate intensive and organic farming practices in terms of producing sufficient food to feed the world, effects on the environment, animal welfare and relative costs. 2.1.6 Ecologists study the relationships between organisms and the environment. These relationships become disturbed when changes occur in the environment, often as a result of human activity. You need to be able to: understand that organisms are interdependent; organisms that live successfully in a habitat are adapted to their environment; understand some of the effects of environmental change on organisms. be able to interpret food chains; understand that there is a limit to the number of trophic levels in food chains. be able to interpret food webs. be able to produce a food web from data food provided. recall that intensive farming (and the burning of fossil fuels) cause changes to the environment that affect organisms. understand how changes in the environment are affecting plant flowering times, animal behaviour and the distribution of animals and plants. be able to interpret data on climate change; explain how the effects of environmental change on plants and animals will affect food webs. 2.1.7 Selective breeding In addition to farming methods, another way that scientists improve the characteristics of plants and animals that are important to humans is by artificial selection or selective breeding. You need to be able to: understand the principles of selective breeding. understand that people can select the characteristics they want to breed in plants and animals. describe the process of selective breeding involving the: o selection of parents with desired traits and characteristics; o cross breeding; o selection and rejection of suitable offspring over many generations; explain how selective breeding can contribute to improved agricultural yields. explain that a selective breeding programme may reduce the gene pool leading to problems (reduction in variation, accumulation of harmful recessive characteristics). 2.1.8 A similar type of selection to the one that plant and animal breeders use occurs in nature. It is called natural selection. When the environment changes, the process of natural selection leads to evolution. The theory of evolution tries to explain why at least 3 million different species of organism inhabit the planet. You need to be able to: understand how the process of natural selection leads to evolution. know that sexual reproduction produces variation in the offspring. understand that some variation is useful and enables organisms to survive in changing environments. understand how sexual reproduction produces variation in the offspring; understand the principles of natural selection. know that scientists use similarities and differences between organisms to classify and identify them. interpret data on evidence for natural selection; explain why natural selection could have led to evolution in a changing environment; explain how recent scientific discoveries may change our understanding of natural selection (questioned validity of peppered moth data) and evolution (recent fossil discoveries by scientists changing evolutionary thinking, e.g., human evolution; evolution of flight in birds). 2.1.9 Genetics Scientists can use their knowledge of genetics to improve the characteristics of organisms that are important to humans. You need to be able to: understand the mechanism of monohybrid inheritance; understand the principles of genetic engineering. state that characteristics can be passed from one generation to the next. explain how characteristics can be passed from one generation to the next. recognise dominant and recessive characteristics and explain that these depend on dominant and recessive alleles: state that alleles are different versions of the same gene; explain a monohybrid cross involving dominant and recessive alleles; use and explain the terms homozygous and heterozygous; recognise the process of genetic engineering as the transfer of foreign genes into the cells of animals, plants or microorganisms; recognise some potential advantages and risks of genetic engineering and selective breeding; recognise ethical dilemmas concerned with genetic engineering. describe the principles of genetic engineering: o selection of desired characteristics; o isolation of genes; o replication; o insertion; evaluate potential advantages (improved characteristics of plants and animals) and disadvantages of genetic engineering and selective breeding (escape of foreign genes; safety of food products; ethical issues). 2.2 Humans as living organisms This section looks at life processes in humans. Workers in the medical profession need to understand how the human body functions and what to look for when things go wrong. We also need to be aware of how our lifestyle, the environment and our genetics could improve our health or contribute to disease. This section links with section 2.1 Living organisms, in that these essential life processes are important to other living organisms. 2.2.1 Moving substances around the body Understanding of our respiratory and circulatory systems help healthcare professionals to treat conditions when these systems do not function properly. Sports. scientists study these to help to improve our lifestyles and athletic performance. You need to be able to: understand the function of the respiratory system; understand how the circulatory system transports oxygen, food substances and waste products; understand the processes of aerobic and anaerobic respiration. name and locate the main parts of the breathing system (trachea, diaphragm, ribcage, lungs); state the functions of the main parts of the breathing system: o lungs for gaseous exchange; o the diaphragm, ribs and intercostal muscles move to inhale and exhale; state that exhaled air: o contains less oxygen than inhaled air; o contains more carbon dioxide than inhaled air; o contains more moisture than inhaled air; o is warmer than inhaled air. state the word equation for aerobic respiration: glucose + oxygen → carbon dioxide + water (+energy) state the symbol equation for aerobic respiration: C6H12O6 + 6O2 → 6CO2 + 6H2O (+ energy) state that sugar reacts with oxygen in the cells to release energy and that the process is called respiration. explain that during exercise the body may respire anaerobically; state the word equation for anaerobic respiration: glucose → lactic acid + energy; state that anaerobic respiration releases much less energy than aerobic. explain fatigue in terms of lactic acid build up; why lactic acid needs to be removed, and oxygen debt. 2.2.1 Moving substances around in the body Understanding of our respiratory and circulatory systems help healthcare professionals to treat conditions when these systems do not function properly. Sports. scientists study these to help to improve our lifestyles and athletic performance. You need to be able to: understand the function of the respiratory system; understand how the circulatory system transports oxygen, food substances and waste products; understand the processes of aerobic and anaerobic respiration. explain that during exercise, breathing and pulse rates increase to deliver oxygen and glucose to muscles more quickly; state that carbon dioxide from respiration is removed from the body by the respiratory system. explain that high levels of CO2 in the blood are toxic and must be removed from the body by the respiratory system; name and locate the main parts of the lungs (bronchi, bronchioles, alveoli); describe how the parts of the respiratory system work together to bring about gaseous exchange respiratory tree, alveoli, blood); describe the changes in position of the ribs and diaphragm that cause inhalation and exhalation; state the approximate percentages of gases in inhaled and exhaled air. explain that when increased CO2 levels in the blood are detected the brain then brings about an increase in breathing rate; explain how the alveoli are adapted for efficient gaseous exchange; explain the way in which inhalation and exhalation are brought about by pressure changes. state that the heart pumps blood; state that the blood moves around the body in arteries, capillaries and veins. describe how the parts of the circulatory system work (heart to pump blood to body and lungs; arteries transport blood away from the heart; veins transport blood to the heart; capillaries and the exchange of materials); name and locate parts of the heart and describe their functions (left and right ventricles, left and right atria, semilunar, tricuspid and bicuspid valves). explain the advantage of the double circulatory system in mammals (differences in pressure in systemic and pulmonary systems); explain the adaptations of arteries (thick, muscular, elastic), veins (presence of valves) and capillaries (onecell thick). state that the blood is a fluid: o transporting food and oxygen to cells; o removing waste products; state that blood is made up of red blood cells, white blood cells, platelets and plasma; state the function of plasma in transporting foods, hormones, water and waste products around the body. explain that haemoglobin in red blood cells reacts with oxygen in the lungs forming oxyhaemoglobin and the reverse of this reaction happens in the tissues; state the word equation: haemoglobin + oxygen ⇌ oxyhaemoglobin. 2.2.2 Co-ordination and homeostasis Two systems help to coordinate the activities and development of our bodies and keep our internal environment constant . the nervous system, using electrical impulses, and endocrine system, using chemicals called hormones. You need to be able to: recall how the nervous system helps us to respond to our environment; recall that hormones help to control blood sugar and control our growth and development. recall that the nervous system helps us to deal rapidly with situations such as keeping our body temperature constant at 37°C. recall that hormones bring about slower changes in our bodies, such as controlling our growth and development; state that the pancreas produces a hormone called insulin that controls levels of blood sugar. know that the nervous system uses nerves to communicate information rapidly around the body coordinated by the central nervous system (brain and spinal cord). describe the passage of the nerve impulse through a reflex arc. explain how changes in the diameter of the blood vessels of the skin (vasodilation and vasoconstriction) are controlled by the nervous system and help to keep body temperature constant. state the function of insulin; explain that people deficient in insulin suffer from diabetes, where there is fluctuation in blood sugar levels; recall that treatment of diabetes is controlled by diet or insulin injection. explain that blood temperature and glucose are monitored by receptors which transmit information to the brain, bringing into place control mechanisms. explain how one way in which insulin reduces blood sugar levels is by converting excess blood glucose to glycogen in the liver; explain that the dosage of insulin depends upon diet and activity; explain the term homeostasis and how, in blood sugar regulation, it is achieved by negative feedback mechanisms. 2.2.3 Disease caused by micro-organisms Most organisms are completely harmless, but a few cause disease. Scientists record and track the spread of disease across countries and around the world. In some instances, or at least not until they have carried out the necessary research, scientists are not certain what type of organism has caused a particular outbreak, or why that organism has begun to infect humans. Some of these new human diseases could severely affect the sizes of human populations over the coming years. You need to be able to: recall that some diseases are caused by microorganisms; know how these microorganisms are spread; understand how our immune system helps to fight and prevent infection; know that antibiotics may be needed to fight some diseases caused by bacteria. recall that some bacteria and all viruses are examples of microorganisms that cause disease; recall three examples of diseases caused by microorganisms. recall examples of infections caused by viruses in humans (measles; mumps; rubella; polio) and other animals (foot and mouth); recall examples of infections caused by bacteria (tuberculosis; infections from Staphylococcus aureus); recall examples of infection caused by fungi (athlete.s foot, ringworm). recall how harmful microorganisms are spread (by droplets in air; by dust; by touch; by faeces; by animals; by blood); recall ways to protect against harmful microorganisms (personal hygiene; using disinfectants, antiseptics, heat and radiation; protective clothing and isolation). recall that when a person gets a disease, the body produces chemicals called antibodies that attack the microorganisms causing the disease; recall that we can cause our bodies to produce antibodies to fight off diseases by immunisation. explain how harmful microorganisms are spread (by droplets in air; by dust; by touch; by faeces; by insects; by blood); explain how, for each method of transmission, the spread of microorganisms is reduced. interpret data that scientists use to track the outbreak and spread of a disease. explain that our skin is a barrier to infection, and explain that blood clotting bridges that barrier if the skin becomes broken; explain that when a person gets a disease the body produces chemicals called antibodies that attack the microorganisms causing the disease. 2.2.4 Diseases caused by micro-organisms (some sort of mistake here) Most organisms are completely harmless, but a few cause disease. Scientists record and track the spread of disease across countries and around the world. In some instances, or at least not until they have carried out the necessary research, scientists are not certain what type of organism has caused a particular outbreak, or why that organism has begun to infect humans. Some of these new human diseases could severely affect the sizes of human populations over the coming years. You need to be able to: recall that some diseases are caused by microorganisms; know how these microorganisms are spread; understand how our immune system helps to fight and prevent infection; know that antibiotics may be needed to fight some diseases caused by bacteria. state how tobacco, solvents, alcohol and recreational drugs can affect physical and mental health; know about the effects of passive smoking. interpret data on the misuse of substances; recognise that some misused drugs can also be the source of medicinal drugs (opiates); recognise that scientific opinion has changed, and that the recreational drug cannabis has been used to reduce suffering in patients with multiple sclerosis. recognise that some diseases (cystic fibrosis; Huntington.s chorea) have genetic causes. use a knowledge of genetics to explain the inheritance of single gene disorders caused by recessive alleles (cystic fibrosis) and dominant alleles (Huntington.s chorea); use a knowledge of genetics to explain why some people are carriers of single gene disorders.